Presser-foot mechanism for sewing machines



Oct. 5,1926. I I $692,140

8. W. AVIS PRESSER Fob'r MECHANISM. FOR SEWING MACHINES Original Filed Deb. 31 1923 Patented per. 5, 1926.

UNITED STATES SAMUEL AVIS, OF WEST HARTFORD, CONNECTICUT.

PRESSER-FOOT MECHANISM FOR SEWING MACHINES.

Application filed This invention relates to the presser foot mechanisms of sewing machines, particularly machines which are designed to run at high speeds, and it is illustrated as'adapted to an overseam machine of the type illustrated and described in my application for Patent #393,223 filed July 1, 1920;

The presser foot is lifted eachtime the feed dogs rise and feed the work. To ensure satisfactory operation the presser foot should closely follow the vertical movements of the feed dogs and keep a uniform pressure on the work. In machines of the type referred to in which the mechanisms are run several thousand revolutions per minute the -speed is'such that the ordinary presser foot controlling means does not act quickly enough when a light return spring is used,

and the employment of a heavy return spring is objectionable; With a light return spring at high speeds the tendency is for the presser foot to remain elevated and the work fail to feed, and a heavy return spring exerts too .much pressure resulting, in excessive wear, undesired noise and a reduction of the speed of operation. I

The object of the present invention is to arrange presser foot controlling means in such manner that the presser foot will at all speeds of the machine exert the required pressure upon the work, especially when the feed dogs are down below the work plate and are moving backward.

In orderto attain this object and overcome the objections incident to the operation of the prior presser foot mechanisms, means,

such for instance as a tension screw, are arranged togive the return spring the necessary initial tension, and means, such. as a ward movement of the return spring after the presser foot has been lifted the required distance, and ensure its quick return, or dog following movements, the checking means being so mounted that when it is desired to lift the presser foot for the insertion of work beneath it, these means will be moved out of checking position by the first part of the movement of the lifter lever that is provide'd for lifting the presser foot, so that the presser f t will be free to be lifted by the continued movement of the lifter lever.

When the lifter lever. is moved to allow the v presser foot to return to normal operating ing the finger forward the tongue check screw, are arranged to limit the up- 7 19 that is December 31, 1923, Serial No. 683,673. Renewed March 12, 1926.

position the checking means are coincidently returned to position for functioning when the machine is operated.

In the accompanying drawings Fig. 1 shows a-plan of a presser foot mechanism which embodies the invention. Fig. 2 shows a side elevation of the same. Fig. 3 shows a side elevation of the means for releasing the checking means and lifting the presser foot.

The presser foot 1 of any suitable shape is pivotally hung upon the lower'end of a finger 2 so as toextend above the feed dogs 3. The upper end of the finger is adjust ably fastened to a hub 4 that projects forwardly from the front end of the presser foot arm 5 which is attached to a shaft 6 that extends horizontally across the machine from side to side. The finger has a headed stud 7 that is drawn into the hub by a spring 8 so as to normally retain a tongue 9 on the end of the hub in a groove '10 in the inside of the finger. This holds the finger in. fixed relation .to the oscillatory arm. By grasping the knob 11 and draw an groove may be disengaged and then the finger may be turned up so astothrow the presser foot out of operative position.

On the rear end of the presser arm shaft is a rocker plate12. This plate is fastened to'the shaft by a key 13 in the shaft that extends into a slot 14 in the hub of the plate so that the shaft and plate may have small independent rotary movements and then one will rotate the other.

One end'of the return spring 15 is held by a screw stud 16. The other end of the return spring bears upon a 18 projecting The initial tension or pressure of the return spring upon the roll is given by the screw threaded through the fixed lug 20 against the spring.

The check screw 21 is threaded through the end of an angle lever 22 and is held in' adjusted position by a lock nut 23. The lever is pivotally mounted upon the stud l6 .and is yieldingly held by a spring 24 on its rear end so that normally the check screw stands 'over the return spring.

The rear end of the angle level has a clown-turned lug 25 adjacent to and in the path of the portion 26 of the rocker plate on roll 17 on a stud from the rear side of the arm.

the arm shaft. A lifter lever 27 is pivoted to the casing adjacent to the rocker plate so as to engage therewith. A guard plate 28. is fastened to the casing so as to extend over the end of the lever adjacent to the check screw for the purpose of backing the lever and reventing it from being sprung up under t e impulses due to the contact of the return spring with the checking screw. This plate also guards the swinging end of the lever and relieves the pivot stud of strains.

The check screw is adjusted so that the spring will engage the tip of the screw and rebound, when the presser foot is lifted sufficiently high during the operation of the machine, to properlyperform its function. With this arrangement a relatively light re-' turn spring which will offer but little resistance to the lifting of the presser foot can be used and yet the presser foot will return quickly and will not remain raised when the machine is running rapidly. In order to lift the presser .foot the lifter lever at the rear is turned up. Owing to the lost mot-ion connection of the rocker plate with the presser the return spring may the feed dogs,

the operation arm shaft the first part of the movement of the lifterlever causes the rocker plate to engage the lug and swing the angle lever against its spring so asto carry the check screw from over the top of the return spring, and the continued movement of the lifter lever then through the rocker plate rotates the shaft and lifts the presser foot. If the lifter lever is turned way up the rounded end 29 of the rocker plate engages the shoulder 30 on the lifter lever and holds the parts with the presser foot raised. When the lifter lever is turned down the presser foot is allowed to drop, and then the angle lever is swung by its s ring. so as to carry the check screw over t e return spring in position to engage and check the upward movement of the return spring and cause it to return more quickly than it would if the check screw were not provided. By adjusting the tension screw the initial pressure of be varied according to the thickness and character of the material being stitched, and the check screw may be adjusted so as to limit the upward movement of the return :Jprin g and cause it to act quickly on its downward movement and ensure that the presser foot closely follow the downward movements of the feed dogs. The provision of the checking screw enables a lighter return-spring to be used, and a lighter return spring is more flexible and does not offer as much resistance to the upward movement of \and consequently resistance to of the machine, as a heavy spring. I i The invention claimed is:

- 1. A sewing machine presser 'foot mechanism comprising a' pivoted presser foot arm, a spring pushing the free end ofsaid arm downward, a finger pi'votally connected with the free end of said ,arm, yielding means normally retaining the finger rigi with relation to the arm, said yielding means permitting disengagement of the finger from the arm and allowing. the finger to be swung upward, and a presser foot attached to the free end of said finger.

1 2. A sewing machine presser foot mechanism comprising a pivoted presser foot arm, a spring pushing the free end of said arm downward, a finger connected with said arm by a sliding pivot, yielding means normally retaining the finger rigid with relation to the arm, said means being disengaged by drawing the finger sidewise from the arm, and a presser foot attached to the free end of said finger. I I

3. A sewing machine presser foot mechanism comprising a pivoted presser foot arm, a spring pushing the free end of said arm downward, a finger connected with said arm by a sliding pivot, said finger and arm having a tongue and groove engagen'lcut, a spring engaging said pivot and normally rctaining the parts with the tongue and groove engage-d. said tongue and groove being disengaged by drawing the finger sidewise from thearm, and a presser foot attached to the free end of said finger.

4. A nism comprising a pivoted presser foot arm, a presser foot connected with the free end of said arm, a spring pushing'the free end of said arm downward. means for in'iparting in initial tension to said spring, and means sewing machine presser foot mechaengaged bythe spring during the upward movement of the presser foot arm for limiting the upward movement of said spring.

5. A sewing machine presser foot mechanism comprising a pivoted presser foot arm, a presser foot connected with the free end of said arm, a spring pushing the free end of said arm downward, an adjustable screw imparting an initial tension to said spring, and a'n adjustable screw for limiting the upward movementof said spring.

6. A sewing machine presser footmechanism comprising a pivoted presser foot arm, a presser foot connected with the free end of said arm, a spring pushingthe free end of said arm downward, adjustable means for imparting an initial tension to said spring, adjustable means for limiting the upward movement of said spring, and means for raising the free end of said arm and lifting the presser foot out of operative position.

7. A sewing machine presser foot mecha- -nism comprising a pivoted presser foot arm,

a presser foot connected with the free end of said arm, a spring pushing the free end of said arm downward, means for iniparting an initial tension to said spring, means for limiting-the upward movement of said raising the end of.

spring, and means for moving said limitin means out of the path of said spring an said arm.

8. Asewing machine presser foot mechanism comprising a pivoted presser foot arm,

- a presser foot connected with the free end of said arm, a spring pushing the free end of said arm downward, an oscillatory angle lever, a screw carried by said lever and 'mally adapted to limit the upward movement of said spring, and means for oscillating said lever and carrying said screw out of the path of said spring. V

9. A sewing machine presser foot mechanism comprising an oscillatory presser foot arm, a presser foot connected-with the free end of said arm, a spring pushing the free end of said arm downward, an oscillatory angle lever, a screw carried'by said lever and adapted to check the upward movement of said spring, and. a lifter lever for oscilarm for 'free end of sald arm, a spring free end of said arm downward,'an angle lating said angle lever and the presser foot first moving the screw out of the path of the spring and then lifting the presser foot.

10. A sewing machine presser foot mechanism comprising a presser foot arm, an 0'scillatory shaft supporting said arm, a rocker plate having a lost motion connection with said shaft, a presser foot connected with/the pushing the lever, a screw carried by said lever and adapted to limit the upward movement of said spring, the other-end of said lever being adapted'to be engaged by the rocker plate, and a lifter lever adapted to engage the rocker plate'and through it oscillate-the lever carrying the check screw and the arm carrying the presser foot.

y 11.' A sewing machine presser anism comprsing a I foot mechpresser foot arm, an oscillatory shaft supporting said arm, a rocker norplate having a'lost motion connection with said shaft, a presser foot connected with the free end of said arm, aspring pushing the free end of said arm downward, -an angle lever, a screw. carried by said lever and adapted to limit the [upward movement of said spring, the other end .of said lever adapted to be engaged by the rocker plate, and a lifter lever adapted to engage the ,rocker plate and through 'it oscillate the angle lever so as to move the check screw from the path of the spring and oscillate the arm carrying the presser 'the presser foot, said lifter plate being adapted to engage an presser foot raised.

12. A sewing machine presser foot mechanism comprising a pivoted presser foot arm, a presser foot connected with the free end of said arm, a spring pushing the free end of said arm downward, an adjustable screw for imparting an initial tension to said spring, an adjustable screw for limiting the upward movement of said spring, and a lifter lever lever and rocker d hold'the foot so as to lift for moving said limiting screw out oflthe path of said sprin said arm, and retaining tions.

13. A sewing machine presser foot mechanism comprising an oscillatory presseigfo'ot arm, a presser end of said arm, end of said arm angle lever, a screw carri vadapted to check the upward movement of said-spring, a guard plate-for retaining and guiding the end of the angle lever adjacent to the check screw, and means for oscillating said angle lever and the presser foot first moving the screw out of the path of spring and then lifting the presser foot.

a spring pushing the free d by said lever and the and raising the end of them in such p0s1-' foot connected'with the free downward, an oscillatory arm for 

